Catalyst converters are used as apparatus for cleaning exhaust gases of internal combustion engines of cars. Such a catalyst converter is provided in the passage of an exhaust pipe so as to remove carbon monoxide, hydrocarbon, and other noxious components in the exhaust, and to clean the exhaust.
In such a catalyst converter, a catalyst carrier is formed of ceramics to be in the form of a honeycomb such as of a columnar block and has a catalyst metal deposited on it to form a catalyst body. Such catalyst body made of ceramics is contained and held in an exhaust pipe or a case connected with it so that exhausts may pass through the catalyst body and may contact the catalyst metal to remove the above-mentioned components.
In the above-described catalyst converter, the catalyst carrier is shaped of ceramics and is therefore so fragile that it is likely to be cracked or broken by vibrations and shocks. Therefore, the life of the catalyst is substantially shortened due to the above-mentioned cracking and breaking. Thus, there is a problem with respect to the durability of the catalyst converter as above described.
Particularly, a motorcycle is required to have sportiness characteristics differing from those of an automobile, and therefore shock absorbers are provided taking such sportiness characteristics into consideration and as a result the motorcycle will be subjected to more vibrations and large shocks. In case the above-described type of catalyst converter is employed on the motorcycle, such vibrations and shocks will act on the catalyst converter to crack or break the catalyst body. In order to prevent such cracking or breaking, the holding of the catalyst body must be taken into consideration.
In the case of actually holding the catalyst body, such holding is generally provided by a case in the exhaust system. Because the case is made of a steel plate but the catalyst body is made of ceramics, the following problem will occur in holding the catalyst body in the case.
Because the catalyst body is fitted in the case while cold and is assembled while cold, and because the parts become heated when the exhaust is to be cleaned, the difference in the thermal expansion between them will cause a clearance to be made between the case and catalyst body and, by the vibrations or the like of the vehicle, the catalyst body in the case will be staggered and as a result will be cracked or broken as mentioned above. Therefore, it has been suggested to provide a corrugated elastic plate in the case so as to hold the catalyst body. However, in this case the catalyst body will not be held well while hot in the axial direction, will slide in the axial direction in the case, will collide on the end surfaces with the front and rear of the case, and will be cracked or broken as mentioned above. Therefore, it has been considered to support the catalyst body by separately providing elastic supporting members in the radial direction and axial direction. However, in this case the number of component parts will increase, the structure will be complicated, and the ease of assembly will be decreased. Thus, it is not desirable to mass-production and cost-reduction to employ this type of converter. Further, the sealability between the case and catalyst body will be reduced and untreated and uncleaned exhaust will be likely to be discharged through the clearance between the catalyst body and case. Thus, it is not desirable to the exhaust cleaning treatment.